internal static IEnumerable <Board> PlayCaptures(Board position) { foreach (var capture in MoveList.SortedCaptures(position)) { var nextPosition = new Board(position, capture); if (!nextPosition.IsChecked(position.SideToMove)) { yield return(nextPosition); } } }
internal static IEnumerable <(Move Move, Board Board)> Play(Board position, int depth, KillerMoves killers, History history) { //1. Is there a known best move for this position? (PV Node) if (Transpositions.GetBestMove(position, out Move bestMove)) { var nextPosition = new Board(position, bestMove); yield return(bestMove, nextPosition); } //2. Try all captures ordered by Mvv-Lva foreach (var capture in MoveList.SortedCaptures(position)) { var nextPosition = new Board(position, capture); if (!nextPosition.IsChecked(position.SideToMove)) { yield return(capture, nextPosition); } } //3. Play quiet moves that have caused a beta cutoff elsewhere if available foreach (Move killer in killers.Get(depth)) { if (position[killer.ToSquare] != Piece.None || !position.IsPlayable(killer)) { continue; } var nextPosition = new Board(position, killer); if (!nextPosition.IsChecked(position.SideToMove)) { yield return(killer, nextPosition); } } //4. Play the remaining quiet moves ordered by history foreach (var move in MoveList.SortedQuiets(position, history)) { if (killers.Contains(depth, move)) { continue; } var nextPosition = new Board(position, move); if (!nextPosition.IsChecked(position.SideToMove)) { yield return(move, nextPosition); } } }